When you first start learning about silencers, one of the terms you'll start seeing tossed around is 'blowback'. In this article we're going to explain:
  1. What blowback is
  2. How different weapons are impacted
  3. How to prevent it from causing problems
Keep in mind that many modern suppressors are specifically designed to reduce blowback; so, if you're worried about it give us a call and we'll help you select a model that will fit your needs.

What is Blowback?

In order to illustrate the concept, let's look at an extremely common semi-automatic weapon: the AR15. When you pull the trigger on your AR15, you'll set in motion a series of events - which can be simplified into these steps:
  1. The powder is ignited - which creates the pressure required to send the bullet down the barrel (with gas expanding behind it)
  2. Once the bullet passes the gas block (which is typically under the front sight post or rail), some of the gas is redirected back through the gas tube and into the chamber
  3. The gas pressure entering the chamber allows the bolt to unlock and cycle - which loads the next round into the chamber
  The gas that goes back into the chamber is called 'blowback'; and, hopefully it's clear that blowback is required to make your AR15 operate correctly.
If you want the ultimate solution, then I'd recommend the Gemtech Suppressed Bolt Carrier also availabe for an AR10.  These bolt carriers work wonders and are adjustable so your weapon will run optimally in either suppressed or unsuppressed mode. (But... Why would you run unsuppressed?) For Piston-Based Weapons, most modern designs include some type of suppressed adjustment.  This adjustment is there specifically to tune the weapon when running a suppressor - and it's easy to use in most cases. For Recoil-Driven Weapons, you generally won't have any serious problems; but, if you do try using a slightly heavier recoil recoil spring.


At the end of the day, blowback isn't a huge issue on most weapons.  If you do run into it, try going through some of the solutions listed here - or
give us a call and we're happy to help.
17 Comment(s)
David Hammond
Generally speaking, is CUP or PSI used to calculate the suppressors capacity? Can I assume I can use the suppressor on any caliber rifle as long the load pressure, doesn’t exceed the manufacturers listed calibers? I have a “can” rated up to 22 hornet, want to put it on 221 fireball rifle. Modern hornet loads list 43,000 cup. As long as I keep the fireball loads below that level—-ok? Thx
Reply Mar 23, 2018 08:00
Jeremy Mallette
Generally PSI although some manufacturers use FPS.
Reply Mar 23, 2018 08:00
Lorenzo Raras
What is the effect of blowback in semi-auto pistols? Do they get dirtier as well or will they have the opposite effect where they don't get as dirty like the bolt guns?
Reply Sep 20, 2017 08:00
Jeremy Mallette
They will get dirtier. It creates more backpressure so there is more carbon in the action.
Reply Sep 25, 2017 08:00
Craig Burge
Do you have any recommendations on pistols. I have an AAC Tirant I got from here in .45. It mounts on an FNX Tac with a Trijicon red-dot. I tell you the crap I get in my face is unreal. Eyes protected obviously, but I feel it in the forehead and cheeks. Plus it craps up the surface of the red dot, I thought at first I oil too much and cut back but what I find on my self is just gray stuff, so just debris. It doesn't happen unsuppressed and I enjoy the quieter shooting experience, but not the stuff in the face. Just thought I would ask. Thanks in advance.
Reply Sep 11, 2017 08:00
Jeremy Mallette
I have an FNX and have not experienced that except when I shoot speer ammo. You might try a different ammo. I also have an HK USP, SIG, and 1911 and all work well with a silencer. The M&P or any gun with a chamber indicator in the barrel will have more than usual blowback.
Reply Sep 19, 2017 08:00
Craig Burge
You called it, cheap dirty ammo. I used just cheap winchester white box, no issue. Nothing in the face. Also didn’t dirty up the red dot either. I was wondering if that was the issue, but never really saw an issue with the steel case ammo before(Dirty yes but….). I just won’t shoot it suppressed, HA HA. Thanks
Reply Mar 23, 2018 08:00
What about blowback on a different style rifle like the BAR or Woodsmaster 7400?
Reply Jul 22, 2017 08:00
Jeremy Mallette
There will be an increase in pressure but how much blowback depends on the model. I have not shot silencers on those firearms so I cannot speak to it.
Reply Jul 24, 2017 08:00
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